“With enormous regret I must announce that I have to cancel all touring for the year as am very unwell due to bi polar disorder,” she writes on her website. “I apologise sincerely for any difficulties this may cause.”

The Irish songstress has struggled with “depression” for years, and last year made headlines with her disturbing, suicidal tweets.

"As you all know I had a very serious breakdown between December and March and I had been advised by my doctor not to go on tour but didn't want to 'fail' or let anyone down as the tour was already booked to coincide with album release,” she wrote on her website.

The 45-year-old singer checked into a hospital for depression earlier this year, after her short-lived marriage to teen drug counselor Barry Herridge in December. The couple split after merely 16 days of marriage.

With a glimmer of hope she says, “While touring will be cancelled I do hope and plan to appear at the Curtis Mayfield tribute in The Lincoln Centre in July.”